U. Holzwarth et U. Essmann, TRANSFORMATION OF DISLOCATION PATTERNS IN FATIGUED COPPER SINGLE-CRYSTALS, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 164(1-2), 1993, pp. 206-210
The transition from the so-called matrix to persistent slip bands (PSB
s) during the fatigue of copper single crystals and the transition of
the dislocation arrangement of PSBs formed at 300 K to that characteri
stic for a deformation temperature of 77 K have been investigated by c
yclic deformation tests and transmission electron microscopy. Strain l
ocalization occurs well before the first fragments of the typical ladd
er-like dislocation arrangement of PSBs can be identified. The results
indicate that the motion of dislocation walls plays an important role
in establishing the ladder-like dislocation arrangement. After a shar
p decrease of the deformation temperature at constant amplitude of res
olved plastic shear strain, only a certain volume fraction of the PSBs
remains active, but with a larger intrinsic amplitude of plastic shea
r strain.